/* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil -*- */
/*
 * Copyright (c) 2004-2005 The Trustees of Indiana University and Indiana
 *                         University Research and Technology
 *                         Corporation.  All rights reserved.
 * Copyright (c) 2004-2021 The University of Tennessee and The University
 *                         of Tennessee Research Foundation.  All rights
 *                         reserved.
 * Copyright (c) 2004-2008 High Performance Computing Center Stuttgart,
 *                         University of Stuttgart.  All rights reserved.
 * Copyright (c) 2004-2005 The Regents of the University of California.
 *                         All rights reserved.
 * Copyright (c) 2008      UT-Battelle, LLC. All rights reserved.
 * Copyright (c) 2010      Oracle and/or its affiliates.  All rights reserved.
 * Copyright (c) 2012      NVIDIA Corporation.  All rights reserved.
 * Copyright (c) 2012-2016 Los Alamos National Security, LLC. All rights
 *                         reserved.
 * Copyright (c) 2015      Cisco Systems, Inc.  All rights reserved.
 * Copyright (c) 2016      Research Organization for Information Science
 *                         and Technology (RIST). All rights reserved.
 * Copyright (c) 2018      FUJITSU LIMITED.  All rights reserved.
 * Copyright (c) 2018-2019 Triad National Security, LLC. All rights
 *                         reserved.
 * Copyright (c) 2022      IBM Corporation.  All rights reserved.
 * Copyright (c) 2024      Google, LLC. All rights reserved.
 * $COPYRIGHT$
 *
 * Additional copyrights may follow
 *
 * $HEADER$
 */


#include "ompi_config.h"
#include "opal/prefetch.h"
#include "opal/mca/mpool/mpool.h"
#include "ompi/runtime/ompi_spc.h"
#include "ompi/constants.h"
#include "ompi/mca/pml/pml.h"
#include "pml_ob1.h"
#include "pml_ob1_hdr.h"
#include "pml_ob1_sendreq.h"
#include "pml_ob1_rdmafrag.h"
#include "pml_ob1_recvreq.h"
#include "ompi/mca/bml/base/base.h"

OBJ_CLASS_INSTANCE(mca_pml_ob1_send_range_t, opal_free_list_item_t,
        NULL, NULL);

void mca_pml_ob1_send_request_process_pending(mca_bml_base_btl_t *bml_btl)
{
    int rc, i, s = opal_list_get_size(&mca_pml_ob1.send_pending);

    /* advance pending requests */
    for(i = 0; i < s; i++) {
        mca_pml_ob1_send_pending_t pending_type = MCA_PML_OB1_SEND_PENDING_NONE;
        mca_pml_ob1_send_request_t* sendreq;
        mca_bml_base_btl_t *send_dst;

        sendreq = get_request_from_send_pending(&pending_type);
        if(OPAL_UNLIKELY(NULL == sendreq))
            break;

        switch(pending_type) {
        case MCA_PML_OB1_SEND_PENDING_SCHEDULE:
            rc = mca_pml_ob1_send_request_schedule_exclusive(sendreq);
            if(OMPI_ERR_OUT_OF_RESOURCE == rc) {
                return;
            }
            break;
        case MCA_PML_OB1_SEND_PENDING_START:
            send_dst = mca_bml_base_btl_array_find(
                    &sendreq->req_endpoint->btl_eager, bml_btl->btl);
            if (NULL == send_dst) {
                /* Put request back onto pending list and try next one. */
                add_request_to_send_pending(sendreq,
                        MCA_PML_OB1_SEND_PENDING_START, true);
            } else {
                MCA_PML_OB1_SEND_REQUEST_RESET(sendreq);
                rc = mca_pml_ob1_send_request_start_btl(sendreq, send_dst);
                if (OMPI_ERR_OUT_OF_RESOURCE == rc) {
                    /* No more resources on this btl so prepend to the pending
                     * list to minimize reordering and give up for now. */
                    add_request_to_send_pending(sendreq,
                            MCA_PML_OB1_SEND_PENDING_START, false);
                    return;
                }
            }
            break;
        default:
            opal_output(0, "[%s:%d] wrong send request type\n",
                    __FILE__, __LINE__);
            break;
        }
    }
}

/*
 * The free call mark the final stage in a request life-cycle. Starting from this
 * point the request is completed at both PML and user level, and can be used
 * for others p2p communications. Therefore, in the case of the OB1 PML it should
 * be added to the free request list.
 */
static int mca_pml_ob1_send_request_free(struct ompi_request_t** request)
{
    mca_pml_ob1_send_request_t* sendreq = *(mca_pml_ob1_send_request_t**)request;
    if(false == sendreq->req_send.req_base.req_free_called) {

        sendreq->req_send.req_base.req_free_called = true;
        PERUSE_TRACE_COMM_EVENT( PERUSE_COMM_REQ_NOTIFY,
                             &(sendreq->req_send.req_base), PERUSE_SEND );

        if (sendreq->req_send.req_base.req_pml_complete) {
            /* make buffer defined when the request is completed,
               and before releasing the objects. */
            MEMCHECKER(
                memchecker_call(&opal_memchecker_base_mem_defined,
                                sendreq->req_send.req_base.req_addr,
                                sendreq->req_send.req_base.req_count,
                                sendreq->req_send.req_base.req_datatype);
            );

            MCA_PML_OB1_SEND_REQUEST_RETURN( sendreq );
        }
        *request = MPI_REQUEST_NULL;
    }
    return OMPI_SUCCESS;
}

static int mca_pml_ob1_send_request_cancel(struct ompi_request_t* request, int complete)
{
#if MPI_VERSION >= 4
    mca_pml_cancel_send_callback(request, complete);
#endif

#if OPAL_ENABLE_FT_MPI
    ompi_communicator_t* comm = request->req_mpi_object.comm;
    mca_pml_ob1_send_request_t* pml_req = (mca_pml_ob1_send_request_t*)request;

    if( REQUEST_COMPLETE(request) ) { /* way to late to cancel this one */
        return OMPI_SUCCESS;
    }
    /* If FT is enabled then we allow canceling requests with a dead process.
     * However, we should not release the request as we don't know if there are
     * no pending fragments. This generates a memory leak as the send requests
     * will never be recovered. */
    if( !ompi_comm_is_proc_active(comm, pml_req->req_send.req_base.req_peer,
                                  OMPI_COMM_IS_INTER(comm)) ) {
        /**
         * As now the PML is done with this request we have to force the pml_complete
         * to true. Otherwise, the request will never be freed.
         */
        opal_output_verbose(10, ompi_ftmpi_output_handle,
                                "Send_request_cancel: cancel granted for request %p because peer %d is dead\n",
                                (void*)request, pml_req->req_send.req_base.req_peer);
        request->req_status._cancelled = true;
        if( NULL != pml_req->rdma_frag ) {
            MCA_PML_OB1_RDMA_FRAG_RETURN(pml_req->rdma_frag);
            pml_req->rdma_frag = NULL;
        }
        mca_pml_ob1_free_rdma_resources(pml_req);
        /* as said above, in theory we should deschedule pending frags and make
         * it PML complete, but that's not easy. Normally, the frags will
         * fail to deliver and the error handling should happen then to
         * call pml_complete when all frags have triggered
         * In the meantime, just mark it MPI complete and hope the BTL does the
         * right thing
         */
        MCA_PML_OB1_SEND_REQUEST_MPI_COMPLETE(pml_req, true);
        return OMPI_SUCCESS;
    }
#endif  /* OPAL_ENABLE_FT_MPI */
    /* we dont cancel send requests by now */
    return OMPI_SUCCESS;
}

static void mca_pml_ob1_send_request_construct(mca_pml_ob1_send_request_t* req)
{
    req->req_send.req_base.req_type = MCA_PML_REQUEST_SEND;
    req->req_send.req_base.req_ompi.req_start = mca_pml_ob1_start;
    req->req_send.req_base.req_ompi.req_free = mca_pml_ob1_send_request_free;
    req->req_send.req_base.req_ompi.req_cancel = mca_pml_ob1_send_request_cancel;
    req->req_rdma_cnt = 0;
    req->req_throttle_sends = false;
    req->rdma_frag = NULL;
    OBJ_CONSTRUCT(&req->req_send_ranges, opal_list_t);
    OBJ_CONSTRUCT(&req->req_send_range_lock, opal_mutex_t);
}

static void mca_pml_ob1_send_request_destruct(mca_pml_ob1_send_request_t* req)
{
    OBJ_DESTRUCT(&req->req_send_ranges);
    OBJ_DESTRUCT(&req->req_send_range_lock);
    assert( NULL == req->rdma_frag );
}

OBJ_CLASS_INSTANCE( mca_pml_ob1_send_request_t,
                    mca_pml_base_send_request_t,
                    mca_pml_ob1_send_request_construct,
                    mca_pml_ob1_send_request_destruct );

/**
 * Completion of a short message - nothing left to schedule.
 */

static inline void
mca_pml_ob1_match_completion_free_request( mca_bml_base_btl_t* bml_btl,
                                           mca_pml_ob1_send_request_t* sendreq )
{
    if( sendreq->req_send.req_bytes_packed > 0 ) {
        PERUSE_TRACE_COMM_EVENT( PERUSE_COMM_REQ_XFER_BEGIN,
                                 &(sendreq->req_send.req_base), PERUSE_SEND );
    }

    /* signal request completion */
    send_request_pml_complete(sendreq);

    /* check for pending requests */
    MCA_PML_OB1_PROGRESS_PENDING(bml_btl);
}

static void
mca_pml_ob1_match_completion_free( struct mca_btl_base_module_t* btl,
                                   struct mca_btl_base_endpoint_t* ep,
                                   struct mca_btl_base_descriptor_t* des,
                                   int status )
{
    mca_pml_ob1_send_request_t* sendreq = (mca_pml_ob1_send_request_t*)des->des_cbdata;
    mca_bml_base_btl_t* bml_btl = (mca_bml_base_btl_t*) des->des_context;

    /* check completion status */
    if( OPAL_UNLIKELY(OMPI_SUCCESS != status) ) {
        opal_output_verbose(mca_pml_ob1_output, 1, "pml:ob1: %s: operation failed with code %d", __func__, status);
        sendreq->req_send.req_base.req_ompi.req_status.MPI_ERROR =
#if OPAL_ENABLE_FT_MPI
            (OMPI_ERR_UNREACH == status ? MPI_ERR_PROC_FAILED : status);
#else
            status;
#endif /* OPAL_ENABLE_FT_MPI */
        mca_bml_base_btl_array_remove(&sendreq->req_endpoint->btl_eager, btl);
        /**
         * Ideally we should release the BTL at this point. Unfortunately as we don't
         * know if other operations are pending on it we can't release it yet (or we
         * will prevent any further callbacks triggering).
         */
    }
    mca_pml_ob1_match_completion_free_request( bml_btl, sendreq );
}

static inline void
mca_pml_ob1_rndv_completion_request( mca_bml_base_btl_t* bml_btl,
                                     mca_pml_ob1_send_request_t* sendreq,
                                     size_t req_bytes_delivered )
{
    if( sendreq->req_send.req_bytes_packed > 0 ) {
        PERUSE_TRACE_COMM_EVENT( PERUSE_COMM_REQ_XFER_BEGIN,
                                 &(sendreq->req_send.req_base), PERUSE_SEND );
    }

    OPAL_THREAD_ADD_FETCH_SIZE_T(&sendreq->req_bytes_delivered, req_bytes_delivered);
    SPC_USER_OR_MPI(sendreq->req_send.req_base.req_ompi.req_status.MPI_TAG, (ompi_spc_value_t)req_bytes_delivered,
                    OMPI_SPC_BYTES_SENT_USER, OMPI_SPC_BYTES_SENT_MPI);

    /* advance the request */
    OPAL_THREAD_ADD_FETCH32(&sendreq->req_state, -1);

    send_request_pml_complete_check(sendreq);

    /* check for pending requests */
    MCA_PML_OB1_PROGRESS_PENDING(bml_btl);
}

/*
 *  Completion of the first fragment of a long message that
 *  requires an acknowledgement
 */
static void
mca_pml_ob1_rndv_completion( mca_btl_base_module_t* btl,
                             struct mca_btl_base_endpoint_t* ep,
                             struct mca_btl_base_descriptor_t* des,
                             int status )
{
    mca_pml_ob1_send_request_t* sendreq = (mca_pml_ob1_send_request_t*)des->des_cbdata;
    mca_bml_base_btl_t* bml_btl = (mca_bml_base_btl_t*)des->des_context;
    size_t req_bytes_delivered;

    /* check completion status */
    if( OPAL_UNLIKELY(OMPI_SUCCESS != status) ) {
        opal_output_verbose(mca_pml_ob1_output, 1, "pml:ob1: %s: operation failed with code %d", __func__, status);
        sendreq->req_send.req_base.req_ompi.req_status.MPI_ERROR =
#if OPAL_ENABLE_FT_MPI
            (OMPI_ERR_UNREACH == status ? MPI_ERR_PROC_FAILED : status);
#else
            status;
#endif
        mca_bml_base_btl_array_remove(&sendreq->req_endpoint->btl_eager, btl);
        /**
         * Ideally we should release the BTL at this point. Unfortunately as we don't
         * know if other operations are pending on it we can't release it yet (or we
         * will prevent any further callbacks triggering).
         */
    }

    /* count bytes of user data actually delivered. As the rndv completion only
     * happens in one thread, the increase of the req_bytes_delivered does not
     * have to be atomic.
     */
    req_bytes_delivered = mca_pml_ob1_compute_segment_length_base ((void *) des->des_segments,
                                                                   des->des_segment_count,
                                                                   sizeof(mca_pml_ob1_rendezvous_hdr_t));

    mca_pml_ob1_rndv_completion_request( bml_btl, sendreq, req_bytes_delivered );
}


/**
 * Completion of a get request.
 */

static void
mca_pml_ob1_rget_completion (mca_pml_ob1_rdma_frag_t *frag, int64_t rdma_length)
{
    mca_pml_ob1_send_request_t *sendreq = (mca_pml_ob1_send_request_t *) frag->rdma_req;
    mca_bml_base_btl_t *bml_btl = frag->rdma_bml;
    size_t frag_remaining;

    /* count bytes of user data actually delivered and check for request completion */
    if (OPAL_LIKELY(0 < rdma_length)) {
        frag_remaining = OPAL_THREAD_SUB_FETCH_SIZE_T(&frag->rdma_bytes_remaining, (size_t)rdma_length);
        SPC_USER_OR_MPI(sendreq->req_send.req_base.req_ompi.req_status.MPI_TAG, (ompi_spc_value_t)rdma_length,
                        OMPI_SPC_BYTES_SENT_USER, OMPI_SPC_BYTES_SENT_MPI);

        if( 0 == frag_remaining ) {  /* this frag is now completed. Update the request and be done */
            OPAL_THREAD_ADD_FETCH_SIZE_T(&sendreq->req_bytes_delivered, frag->rdma_length);
            if( sendreq->rdma_frag == frag )
                sendreq->rdma_frag = NULL;
            MCA_PML_OB1_RDMA_FRAG_RETURN(frag);
        }
    }
    else {
        opal_output_verbose(mca_pml_ob1_output, 1, "pml:ob1: %s: operation failed with code %d", __func__, (int)rdma_length);
        sendreq->req_send.req_base.req_ompi.req_status.MPI_ERROR =
#if OPAL_ENABLE_FT_MPI
            (OMPI_ERR_UNREACH == rdma_length) ? MPI_ERR_PROC_FAILED : (int)rdma_length;
#else
            rdma_length;
#endif
        mca_bml_base_btl_array_remove(&sendreq->req_endpoint->btl_eager, bml_btl->btl);
        /**
         * Ideally we should release the BTL at this point. Unfortunately as we don't
         * know if other operations are pending on it we can't release it yet (or we
         * will prevent any further callbacks triggering).
         */

        /* error fragment is 'delivered' */
        OPAL_THREAD_ADD_FETCH_SIZE_T(&sendreq->req_bytes_delivered, frag->rdma_length);
        if( sendreq->rdma_frag == frag ) {
            sendreq->rdma_frag = NULL;
        }
        MCA_PML_OB1_RDMA_FRAG_RETURN(frag);
    }

    send_request_pml_complete_check(sendreq);

    if( OPAL_LIKELY(0 < rdma_length) ) {
        MCA_PML_OB1_PROGRESS_PENDING(bml_btl);
    }
}


/**
 * Completion of a control message - return resources.
 */

static void
mca_pml_ob1_send_ctl_completion( mca_btl_base_module_t* btl,
                                 struct mca_btl_base_endpoint_t* ep,
                                 struct mca_btl_base_descriptor_t* des,
                                 int status )
{
    mca_bml_base_btl_t* bml_btl = (mca_bml_base_btl_t*) des->des_context;

    if( OPAL_UNLIKELY(OMPI_SUCCESS != status) ) {
        mca_pml_ob1_send_request_t* sendreq = (mca_pml_ob1_send_request_t*)des->des_cbdata;
        opal_output_verbose(mca_pml_ob1_output, 1, "pml:ob1: %s: operation failed with code %d", __func__, status);
        sendreq->req_send.req_base.req_ompi.req_status.MPI_ERROR =
#if OPAL_ENABLE_FT_MPI
            (OMPI_ERR_UNREACH == status ? MPI_ERR_PROC_FAILED : status);
#else
            status;
#endif
        mca_bml_base_btl_array_remove(&sendreq->req_endpoint->btl_eager, btl);
        /** Ideally we should release the BTL at this point. Unfortunately as we don't
         * know if other operations are pending on it we can't release it yet (or we
         * will prevent any further callbacks triggering).
         */
    }
    else {
        /* check for pending requests */
        MCA_PML_OB1_PROGRESS_PENDING(bml_btl);
    }
}

/**
 * Completion of additional fragments of a large message - may need
 * to schedule additional fragments.
 */

static void
mca_pml_ob1_frag_completion( mca_btl_base_module_t* btl,
                             struct mca_btl_base_endpoint_t* ep,
                             struct mca_btl_base_descriptor_t* des,
                             int status )
{
    mca_pml_ob1_send_request_t* sendreq = (mca_pml_ob1_send_request_t*)des->des_cbdata;
    mca_bml_base_btl_t* bml_btl = (mca_bml_base_btl_t*) des->des_context;
    size_t req_bytes_delivered;

    /* check completion status */
    if( OPAL_UNLIKELY(OMPI_SUCCESS != status) ) {
        opal_output_verbose(mca_pml_ob1_output, 1, "pml:ob1: %s: operation failed with code %d", __func__, status);
        sendreq->req_send.req_base.req_ompi.req_status.MPI_ERROR =
#if OPAL_ENABLE_FT_MPI
            (OMPI_ERR_UNREACH == status ? MPI_ERR_PROC_FAILED : status);
#else
            status;
#endif
        mca_bml_base_btl_array_remove(&sendreq->req_endpoint->btl_eager, btl);
        /**
          * Ideally we should release the BTL at this point. Unfortunately as we don't
          * know if other operations are pending on it we can't release it yet (or we
          * will prevent any further callbacks triggering).
          */
        req_bytes_delivered = sendreq->req_send.req_bytes_packed - sendreq->req_bytes_delivered;
    }
    else {
        /* count bytes of user data actually delivered */
        req_bytes_delivered = mca_pml_ob1_compute_segment_length_base ((void *) des->des_segments,
                                                                       des->des_segment_count,
                                                                       sizeof(mca_pml_ob1_frag_hdr_t));
    }

    OPAL_THREAD_ADD_FETCH32(&sendreq->req_pipeline_depth, -1);
    OPAL_THREAD_ADD_FETCH_SIZE_T(&sendreq->req_bytes_delivered, req_bytes_delivered);
    SPC_USER_OR_MPI(sendreq->req_send.req_base.req_ompi.req_status.MPI_TAG, (ompi_spc_value_t)req_bytes_delivered,
                    OMPI_SPC_BYTES_SENT_USER, OMPI_SPC_BYTES_SENT_MPI);

    if(send_request_pml_complete_check(sendreq) == false) {
        mca_pml_ob1_send_request_schedule(sendreq);
    }

    /* check for pending requests */
    MCA_PML_OB1_PROGRESS_PENDING(bml_btl);
}

/**
 * This function is called when the copy of the frag from the GPU buffer
 * to the internal buffer is complete.  Used to support asynchronous
 * copies from GPU to host buffers. Now the data can be sent.
 */
static void
mca_pml_ob1_copy_frag_completion( mca_btl_base_module_t* btl,
                                  struct mca_btl_base_endpoint_t* ep,
                                  struct mca_btl_base_descriptor_t* des,
                                  int status )
{
    int rc;
    mca_bml_base_btl_t* bml_btl = (mca_bml_base_btl_t*) des->des_context;

    des->des_cbfunc = mca_pml_ob1_frag_completion;
    /* Reset the BTL ownership flag as the BTL can free it after completion. */
    des->des_flags |= MCA_BTL_DES_FLAGS_BTL_OWNERSHIP;
    OPAL_OUTPUT((-1, "copy_frag_completion FRAG frag=%p", (void *)des));
    /* Currently, we cannot support a failure in the send.  In the blocking
     * case, the counters tracking the fragments being sent are not adjusted
     * until the function returns success, so it handles the error by leaving
     * all the buffer counters intact.  In this case, it is too late so
     * we just abort.  In theory, a new queue could be created to hold this
     * fragment and then attempt to send it out on another BTL. */
    rc = mca_bml_base_send(bml_btl, des, MCA_PML_OB1_HDR_TYPE_FRAG);
    if(OPAL_UNLIKELY(rc < 0)) {
        opal_output(0, "%s:%d FATAL", __FILE__, __LINE__);
        ompi_rte_abort(-1, NULL);
    }
}

/**
 *  Buffer the entire message and mark as complete.
 */

int mca_pml_ob1_send_request_start_buffered(
    mca_pml_ob1_send_request_t* sendreq,
    mca_bml_base_btl_t* bml_btl,
    size_t size)
{
    const bool need_ext_match = MCA_PML_OB1_SEND_REQUEST_REQUIRES_EXT_MATCH(sendreq);
    size_t hdr_size = sizeof (mca_pml_ob1_rendezvous_hdr_t);
    mca_btl_base_descriptor_t* des;
    mca_btl_base_segment_t* segment;
    mca_pml_ob1_hdr_t* hdr;
    mca_pml_ob1_rendezvous_hdr_t *hdr_rndv;
    struct iovec iov;
    unsigned int iov_count;
    size_t max_data, req_bytes_delivered;
    int rc;

    if (OPAL_UNLIKELY(need_ext_match)) {
        hdr_size = sizeof (hdr->hdr_ext_rndv);
    }

    /* allocate descriptor */
    mca_bml_base_alloc(bml_btl, &des, MCA_BTL_NO_ORDER, hdr_size + size,
                       MCA_BTL_DES_FLAGS_PRIORITY | MCA_BTL_DES_FLAGS_BTL_OWNERSHIP |
                       MCA_BTL_DES_FLAGS_SIGNAL);
    if( OPAL_UNLIKELY(NULL == des) ) {
        return OMPI_ERR_OUT_OF_RESOURCE;
    }
    segment = des->des_segments;

    /* pack the data into the BTL supplied buffer */
    iov.iov_base = (IOVBASE_TYPE*)((unsigned char*)segment->seg_addr.pval + hdr_size);
    iov.iov_len = size;
    iov_count = 1;
    max_data = size;
    if((rc = opal_convertor_pack( &sendreq->req_send.req_base.req_convertor,
                                  &iov,
                                  &iov_count,
                                  &max_data)) < 0) {
        mca_bml_base_free(bml_btl, des);
        return rc;
    }
    req_bytes_delivered = max_data;

    /* build rendezvous header */
    hdr = (mca_pml_ob1_hdr_t*)segment->seg_addr.pval;
    if (OPAL_UNLIKELY(need_ext_match)) {
        hdr_rndv = &hdr->hdr_ext_rndv.hdr_rndv;
        mca_pml_ob1_cid_hdr_prepare (&hdr->hdr_cid, sendreq->req_send.req_base.req_comm);
    } else {
        hdr_rndv = &hdr->hdr_rndv;
    }

    mca_pml_ob1_rendezvous_hdr_prepare (hdr_rndv, MCA_PML_OB1_HDR_TYPE_RNDV, 0,
                                        sendreq->ob1_proc->comm_index,
                                        sendreq->req_send.req_base.req_comm->c_my_rank,
                                        sendreq->req_send.req_base.req_tag,
                                        (uint16_t)sendreq->req_send.req_base.req_sequence,
                                        sendreq->req_send.req_bytes_packed, sendreq);

    ob1_hdr_hton(hdr, hdr->hdr_common.hdr_type, sendreq->req_send.req_base.req_proc);

    /* update lengths */
    segment->seg_len = hdr_size + max_data;

    des->des_cbfunc = mca_pml_ob1_rndv_completion;
    des->des_cbdata = sendreq;

    /* buffer the remainder of the message if it is not buffered yet */
    if( OPAL_LIKELY(sendreq->req_send.req_addr == sendreq->req_send.req_base.req_addr) ) {
        rc = mca_pml_base_bsend_request_alloc((ompi_request_t*)sendreq);
        if( OPAL_UNLIKELY(OMPI_SUCCESS != rc) ) {
            mca_bml_base_free(bml_btl, des);
            return rc;
        }

        iov.iov_base = (IOVBASE_TYPE*)(((unsigned char*)sendreq->req_send.req_addr) + max_data);
        iov.iov_len = max_data = sendreq->req_send.req_bytes_packed - max_data;

        if((rc = opal_convertor_pack( &sendreq->req_send.req_base.req_convertor,
                                      &iov,
                                      &iov_count,
                                      &max_data)) < 0) {
            mca_bml_base_free(bml_btl, des);
            return rc;
        }

        /* re-init convertor for packed data */
        opal_convertor_prepare_for_send( &sendreq->req_send.req_base.req_convertor,
                                         &(ompi_mpi_byte.dt.super),
                                         sendreq->req_send.req_bytes_packed,
                                         sendreq->req_send.req_addr );
    }

    /* wait for ack and completion */
    sendreq->req_state = 2;

    /* request is complete at mpi level */
    MCA_PML_OB1_SEND_REQUEST_MPI_COMPLETE(sendreq, true);

    /* send */
    rc = mca_bml_base_send (bml_btl, des, hdr->hdr_common.hdr_type);
    if( OPAL_LIKELY( rc >= 0 ) ) {
        if( OPAL_LIKELY( 1 == rc ) ) {
            mca_pml_ob1_rndv_completion_request( bml_btl, sendreq, req_bytes_delivered);
        }
        return OMPI_SUCCESS;
    }
    mca_bml_base_free(bml_btl, des );
    return rc;
}


/**
 *  We work on a buffered request with a size smaller than the eager size
 *  or the BTL is not able to send the data IN_PLACE. Request a segment
 *  that is used for initial hdr and any eager data. This is used only
 *  from the _START macro.
 */
int mca_pml_ob1_send_request_start_copy( mca_pml_ob1_send_request_t* sendreq,
                                         mca_bml_base_btl_t* bml_btl,
                                         size_t size )
{
    const bool need_ext_match = MCA_PML_OB1_SEND_REQUEST_REQUIRES_EXT_MATCH(sendreq);
    size_t hdr_size = OMPI_PML_OB1_MATCH_HDR_LEN;
    mca_btl_base_descriptor_t* des = NULL;
    mca_btl_base_segment_t* segment;
    mca_pml_ob1_hdr_t* hdr;
    mca_pml_ob1_match_hdr_t *hdr_match;
    struct iovec iov;
    unsigned int iov_count;
    size_t max_data = size;
    int rc;

    if(NULL != bml_btl->btl->btl_sendi && !need_ext_match) {
        mca_pml_ob1_match_hdr_t match;

        mca_pml_ob1_match_hdr_prepare (&match, MCA_PML_OB1_HDR_TYPE_MATCH, 0,
                                       sendreq->ob1_proc->comm_index,
                                       sendreq->req_send.req_base.req_comm->c_my_rank,
                                       sendreq->req_send.req_base.req_tag,
                                       (uint16_t)sendreq->req_send.req_base.req_sequence);

        ob1_hdr_hton (&match, MCA_PML_OB1_HDR_TYPE_MATCH, sendreq->req_send.req_base.req_proc);

        /* try to send immediately */
        rc = mca_bml_base_sendi( bml_btl, &sendreq->req_send.req_base.req_convertor,
                                 &match, OMPI_PML_OB1_MATCH_HDR_LEN,
                                 size, MCA_BTL_NO_ORDER,
                                 MCA_BTL_DES_FLAGS_PRIORITY | MCA_BTL_DES_FLAGS_BTL_OWNERSHIP,
                                 MCA_PML_OB1_HDR_TYPE_MATCH,
                                 &des);
        if( OPAL_LIKELY(OMPI_SUCCESS == rc) ) {
            /* signal request completion */
            SPC_USER_OR_MPI(sendreq->req_send.req_base.req_ompi.req_status.MPI_TAG, (ompi_spc_value_t)size,
                            OMPI_SPC_BYTES_SENT_USER, OMPI_SPC_BYTES_SENT_MPI);
            send_request_pml_complete(sendreq);
            return OMPI_SUCCESS;
        }

        /* just in case the btl changed the converter, reset it */
        if (size > 0 && NULL != des) {
            MCA_PML_OB1_SEND_REQUEST_RESET(sendreq);
        }
    } else {
        /* allocate descriptor */
        if (OPAL_UNLIKELY(need_ext_match)) {
            hdr_size += sizeof (hdr->hdr_cid);
        }

        mca_bml_base_alloc (bml_btl, &des, MCA_BTL_NO_ORDER, hdr_size + size,
                            MCA_BTL_DES_FLAGS_PRIORITY | MCA_BTL_DES_FLAGS_BTL_OWNERSHIP);
    }
    if( OPAL_UNLIKELY(NULL == des) ) {
        return OMPI_ERR_OUT_OF_RESOURCE;
    }

    segment = des->des_segments;

    if(size > 0) {
        /* pack the data into the supplied buffer */
        iov.iov_base = (IOVBASE_TYPE*)((unsigned char*)segment->seg_addr.pval + hdr_size);
        iov.iov_len  = size;
        iov_count    = 1;
        /*
         * Before copy the user buffer, make the target part
         * accessible.
         */
        MEMCHECKER(
            memchecker_call(&opal_memchecker_base_mem_defined,
                            sendreq->req_send.req_base.req_addr,
                            sendreq->req_send.req_base.req_count,
                            sendreq->req_send.req_base.req_datatype);
        );
        (void)opal_convertor_pack( &sendreq->req_send.req_base.req_convertor,
                                   &iov, &iov_count, &max_data );
         /*
          *  Packing finished, make the user buffer unaccessible.
          */
        MEMCHECKER(
            memchecker_call(&opal_memchecker_base_mem_noaccess,
                            sendreq->req_send.req_base.req_addr,
                            sendreq->req_send.req_base.req_count,
                            sendreq->req_send.req_base.req_datatype);
        );
    }

    /* build match header */
    hdr = (mca_pml_ob1_hdr_t*)segment->seg_addr.pval;
    if (OPAL_UNLIKELY(need_ext_match)) {
        hdr_match = &hdr->hdr_ext_match.hdr_match;
        mca_pml_ob1_cid_hdr_prepare (&hdr->hdr_cid, sendreq->req_send.req_base.req_comm);
    } else {
        hdr_match = &hdr->hdr_match;
    }

    mca_pml_ob1_match_hdr_prepare (hdr_match, MCA_PML_OB1_HDR_TYPE_MATCH, 0,
                                   sendreq->ob1_proc->comm_index,
                                   sendreq->req_send.req_base.req_comm->c_my_rank,
                                   sendreq->req_send.req_base.req_tag,
                                   (uint16_t)sendreq->req_send.req_base.req_sequence);

    ob1_hdr_hton(hdr, hdr->hdr_common.hdr_type, sendreq->req_send.req_base.req_proc);

    /* update lengths */
    segment->seg_len = hdr_size + max_data;

    /* short message */
    des->des_cbdata = sendreq;
    des->des_cbfunc = mca_pml_ob1_match_completion_free;

    /* send */
    rc = mca_bml_base_send_status(bml_btl, des, hdr->hdr_common.hdr_type);
    SPC_USER_OR_MPI(sendreq->req_send.req_base.req_ompi.req_status.MPI_TAG, (ompi_spc_value_t)size,
                    OMPI_SPC_BYTES_SENT_USER, OMPI_SPC_BYTES_SENT_MPI);
    if( OPAL_LIKELY( rc >= OPAL_SUCCESS ) ) {
        if( OPAL_LIKELY( 1 == rc ) ) {
            mca_pml_ob1_match_completion_free_request( bml_btl, sendreq );
        }
        return OMPI_SUCCESS;
    }

    if (OMPI_ERR_RESOURCE_BUSY == rc) {
        /* No more resources. Allow the upper level to queue the send */
        rc = OMPI_ERR_OUT_OF_RESOURCE;
    }

    mca_bml_base_free (bml_btl, des);

    return rc;
}

/**
 *  BTL can send directly from user buffer so allow the BTL
 *  to prepare the segment list. Start sending a small message.
 */

int mca_pml_ob1_send_request_start_prepare( mca_pml_ob1_send_request_t* sendreq,
                                            mca_bml_base_btl_t* bml_btl,
                                            size_t size )
{
    const bool need_ext_match = MCA_PML_OB1_SEND_REQUEST_REQUIRES_EXT_MATCH(sendreq);
    size_t hdr_size = OMPI_PML_OB1_MATCH_HDR_LEN;
    mca_btl_base_descriptor_t* des;
    mca_btl_base_segment_t* segment;
    mca_pml_ob1_hdr_t* hdr;
    mca_pml_ob1_match_hdr_t *hdr_match;
    int rc;

    if (OPAL_UNLIKELY(need_ext_match)) {
        hdr_size += sizeof (hdr->hdr_cid);
    }

    /* prepare descriptor */
    mca_bml_base_prepare_src (bml_btl, &sendreq->req_send.req_base.req_convertor,
                              MCA_BTL_NO_ORDER, hdr_size, &size,
                              MCA_BTL_DES_FLAGS_PRIORITY | MCA_BTL_DES_FLAGS_BTL_OWNERSHIP,
                              &des);
    if( OPAL_UNLIKELY(NULL == des) ) {
        return OMPI_ERR_OUT_OF_RESOURCE;
    }
    segment = des->des_segments;

    /* build match header */
    hdr = (mca_pml_ob1_hdr_t*)segment->seg_addr.pval;
    if (OPAL_UNLIKELY(need_ext_match)) {
        hdr_match = &hdr->hdr_ext_match.hdr_match;
        mca_pml_ob1_cid_hdr_prepare (&hdr->hdr_cid, sendreq->req_send.req_base.req_comm);
    } else {
        hdr_match = &hdr->hdr_match;
    }

    mca_pml_ob1_match_hdr_prepare (hdr_match, MCA_PML_OB1_HDR_TYPE_MATCH, 0,
                                   sendreq->ob1_proc->comm_index,
                                   sendreq->req_send.req_base.req_comm->c_my_rank,
                                   sendreq->req_send.req_base.req_tag,
                                   (uint16_t)sendreq->req_send.req_base.req_sequence);

    ob1_hdr_hton(hdr, hdr->hdr_common.hdr_type, sendreq->req_send.req_base.req_proc);

    /* short message */
    des->des_cbfunc = mca_pml_ob1_match_completion_free;
    des->des_cbdata = sendreq;

    /* send */
    rc = mca_bml_base_send(bml_btl, des, hdr->hdr_common.hdr_type);
    SPC_USER_OR_MPI(sendreq->req_send.req_base.req_ompi.req_status.MPI_TAG, (ompi_spc_value_t)size,
                    OMPI_SPC_BYTES_SENT_USER, OMPI_SPC_BYTES_SENT_MPI);
    if( OPAL_LIKELY( rc >= OPAL_SUCCESS ) ) {
        if( OPAL_LIKELY( 1 == rc ) ) {
            mca_pml_ob1_match_completion_free_request( bml_btl, sendreq );
        }
        return OMPI_SUCCESS;
    }
    mca_bml_base_free(bml_btl, des );
    return rc;
}


/**
 *  We have contiguous data that is registered - schedule across
 *  available nics.
 */

int mca_pml_ob1_send_request_start_rdma( mca_pml_ob1_send_request_t* sendreq,
                                         mca_bml_base_btl_t* bml_btl,
                                         size_t size )
{
    /*
     * When req_rdma array is constructed the first element of the array always
     * assigned different btl in round robin fashion (if there are more than
     * one RDMA capable BTLs). This way round robin distribution of RDMA
     * operation is achieved.
     */
    const bool need_ext_match = MCA_PML_OB1_SEND_REQUEST_REQUIRES_EXT_MATCH(sendreq);
    size_t reg_size, hdr_size = sizeof (mca_pml_ob1_rget_hdr_t);
    mca_btl_base_registration_handle_t *local_handle;
    mca_btl_base_descriptor_t *des;
    mca_pml_ob1_rdma_frag_t *frag;
    mca_pml_ob1_hdr_t *hdr;
    mca_pml_ob1_rget_hdr_t *hdr_rget;
    void *data_ptr;
    int rc;

    bml_btl = sendreq->req_rdma[0].bml_btl;
    if (!(bml_btl->btl_flags & (MCA_BTL_FLAGS_GET | MCA_BTL_FLAGS_ACCELERATOR_GET))) {
        sendreq->rdma_frag = NULL;
        /* This BTL does not support get. Use rendezvous to start the RDMA operation using put instead. */
        return mca_pml_ob1_send_request_start_rndv (sendreq, bml_btl, 0, MCA_PML_OB1_HDR_FLAGS_CONTIG |
                                                    MCA_PML_OB1_HDR_FLAGS_PIN);
    }

    /* at this time ob1 does not support non-contiguous gets. the convertor represents a
     * contiguous block of memory */
    opal_convertor_get_current_pointer (&sendreq->req_send.req_base.req_convertor, &data_ptr);

    local_handle = sendreq->req_rdma[0].btl_reg;

    /* allocate an rdma fragment to keep track of the request size for use in the fin message */
    MCA_PML_OB1_RDMA_FRAG_ALLOC(frag);
    if (OPAL_UNLIKELY(NULL == frag)) {
        return OPAL_ERR_OUT_OF_RESOURCE;
    }

    /* fill in necessary fragment data */
    frag->rdma_req = sendreq;
    frag->rdma_bml = bml_btl;
    frag->rdma_length = size;
    frag->rdma_bytes_remaining = size;
    frag->cbfunc = mca_pml_ob1_rget_completion;
    /* do not store the local handle in the fragment. it will be released by mca_pml_ob1_free_rdma_resources */

    if (OPAL_UNLIKELY(need_ext_match)) {
        hdr_size = sizeof (hdr->hdr_ext_rget);
    }

    reg_size = bml_btl->btl->btl_registration_handle_size;
    hdr_size += reg_size;

    /* allocate space for get hdr + segment list */
    mca_bml_base_alloc(bml_btl, &des, MCA_BTL_NO_ORDER, hdr_size,
                       MCA_BTL_DES_FLAGS_PRIORITY | MCA_BTL_DES_FLAGS_BTL_OWNERSHIP |
                       MCA_BTL_DES_FLAGS_SIGNAL);
    if( OPAL_UNLIKELY(NULL == des) ) {
        /* NTH: no need to reset the converter here. it will be reset before it is retried */
        MCA_PML_OB1_RDMA_FRAG_RETURN(frag);
        return OMPI_ERR_OUT_OF_RESOURCE;
    }

    /* save the fragment for get->put fallback */
    sendreq->rdma_frag = frag;

    /* build match header */
    hdr = (mca_pml_ob1_hdr_t *) des->des_segments->seg_addr.pval;
    if (need_ext_match) {
        hdr_rget = &hdr->hdr_ext_rget.hdr_rget;
        mca_pml_ob1_cid_hdr_prepare (&hdr->hdr_cid, sendreq->req_send.req_base.req_comm);
    } else {
        hdr_rget = &hdr->hdr_rget;
    }

    /* TODO -- Add support for multiple segments for get */
    mca_pml_ob1_rget_hdr_prepare (hdr_rget, MCA_PML_OB1_HDR_FLAGS_CONTIG | MCA_PML_OB1_HDR_FLAGS_PIN,
                                  sendreq->ob1_proc->comm_index,
                                  sendreq->req_send.req_base.req_comm->c_my_rank,
                                  sendreq->req_send.req_base.req_tag,
                                  (uint16_t)sendreq->req_send.req_base.req_sequence,
                                  sendreq->req_send.req_bytes_packed, sendreq,
                                  frag, data_ptr, local_handle, reg_size);

    ob1_hdr_hton(hdr, hdr->hdr_common.hdr_type, sendreq->req_send.req_base.req_proc);

    des->des_cbfunc = mca_pml_ob1_send_ctl_completion;
    des->des_cbdata = sendreq;

    /**
     * Well, it's a get so we will not know when the peer will get the data anyway.
     * If we generate the PERUSE event here, at least we will know when we
     * sent the GET message ...
     */
    if( sendreq->req_send.req_bytes_packed > 0 ) {
        PERUSE_TRACE_COMM_EVENT( PERUSE_COMM_REQ_XFER_BEGIN,
                                 &(sendreq->req_send.req_base), PERUSE_SEND );
    }

    /* send */
    rc = mca_bml_base_send(bml_btl, des, hdr->hdr_common.hdr_type);
    if (OPAL_UNLIKELY(rc < 0)) {
        MCA_PML_OB1_RDMA_FRAG_RETURN(frag);
        sendreq->rdma_frag = NULL;
        mca_bml_base_free(bml_btl, des);
        return rc;
    }

    return OMPI_SUCCESS;
}


/**
 *  Rendezvous is required. Not doing rdma so eager send up to
 *  the btls eager limit.
 */

int mca_pml_ob1_send_request_start_rndv( mca_pml_ob1_send_request_t* sendreq,
                                         mca_bml_base_btl_t* bml_btl,
                                         size_t size,
                                         int flags )
{
    const bool need_ext_match = MCA_PML_OB1_SEND_REQUEST_REQUIRES_EXT_MATCH(sendreq);
    size_t hdr_size = sizeof (mca_pml_ob1_rendezvous_hdr_t);
    mca_btl_base_descriptor_t* des;
    mca_btl_base_segment_t* segment;
    mca_pml_ob1_hdr_t* hdr;
    mca_pml_ob1_rendezvous_hdr_t *hdr_rndv;
    int rc;

    if (OPAL_UNLIKELY(need_ext_match)) {
        hdr_size = sizeof (hdr->hdr_ext_rndv);
    }

    /* prepare descriptor */
    if(size == 0) {
        mca_bml_base_alloc (bml_btl, &des, MCA_BTL_NO_ORDER, hdr_size, MCA_BTL_DES_FLAGS_PRIORITY |
                            MCA_BTL_DES_FLAGS_BTL_OWNERSHIP);
    } else {
        MEMCHECKER(
            memchecker_call(&opal_memchecker_base_mem_defined,
                            sendreq->req_send.req_base.req_addr,
                            sendreq->req_send.req_base.req_count,
                            sendreq->req_send.req_base.req_datatype);
        );
        mca_bml_base_prepare_src (bml_btl, &sendreq->req_send.req_base.req_convertor,
                                  MCA_BTL_NO_ORDER, hdr_size, &size,
                                  MCA_BTL_DES_FLAGS_PRIORITY | MCA_BTL_DES_FLAGS_BTL_OWNERSHIP |
                                  MCA_BTL_DES_FLAGS_SIGNAL, &des);
        MEMCHECKER(
            memchecker_call(&opal_memchecker_base_mem_noaccess,
                            sendreq->req_send.req_base.req_addr,
                            sendreq->req_send.req_base.req_count,
                            sendreq->req_send.req_base.req_datatype);
        );
    }

    if( OPAL_UNLIKELY(NULL == des) ) {
        return OMPI_ERR_OUT_OF_RESOURCE;
    }
    segment = des->des_segments;

    /* build hdr */
    hdr = (mca_pml_ob1_hdr_t*)segment->seg_addr.pval;

    if (OPAL_UNLIKELY(need_ext_match)) {
        hdr_rndv = &hdr->hdr_ext_rndv.hdr_rndv;
        mca_pml_ob1_cid_hdr_prepare (&hdr->hdr_cid, sendreq->req_send.req_base.req_comm);
    } else {
        hdr_rndv = &hdr->hdr_rndv;
    }

    mca_pml_ob1_rendezvous_hdr_prepare (hdr_rndv, MCA_PML_OB1_HDR_TYPE_RNDV, flags |
                                        MCA_PML_OB1_HDR_FLAGS_SIGNAL,
                                        sendreq->ob1_proc->comm_index,
                                        sendreq->req_send.req_base.req_comm->c_my_rank,
                                        sendreq->req_send.req_base.req_tag,
                                        (uint16_t)sendreq->req_send.req_base.req_sequence,
                                        sendreq->req_send.req_bytes_packed, sendreq);

    ob1_hdr_hton(hdr, hdr->hdr_common.hdr_type, sendreq->req_send.req_base.req_proc);

    /* first fragment of a long message */
    des->des_cbdata = sendreq;
    des->des_cbfunc = mca_pml_ob1_rndv_completion;

    /* wait for ack and completion */
    sendreq->req_state = 2;

    /* send */
    rc = mca_bml_base_send(bml_btl, des, hdr->hdr_common.hdr_type);
    if( OPAL_LIKELY( rc >= 0 ) ) {
        if( OPAL_LIKELY( 1 == rc ) ) {
            mca_pml_ob1_rndv_completion_request( bml_btl, sendreq, size );
        }
        return OMPI_SUCCESS;
    }
    mca_bml_base_free(bml_btl, des );
    return rc;
}

void mca_pml_ob1_send_request_copy_in_out( mca_pml_ob1_send_request_t *sendreq,
                                           uint64_t send_offset,
                                           uint64_t send_length )
{
    mca_pml_ob1_send_range_t *sr;
    opal_free_list_item_t *i;
    mca_bml_base_endpoint_t* bml_endpoint = sendreq->req_endpoint;
    int num_btls = mca_bml_base_btl_array_get_size(&bml_endpoint->btl_send);
    int n;
    double weight_total = 0;

    if( OPAL_UNLIKELY(0 == send_length) )
        return;

    i = opal_free_list_wait (&mca_pml_ob1.send_ranges);

    sr = (mca_pml_ob1_send_range_t*)i;

    sr->range_send_offset = send_offset;
    sr->range_send_length = send_length;
    sr->range_btl_idx = 0;

    for(n = 0; n < num_btls && n < mca_pml_ob1.max_send_per_range; n++) {
        sr->range_btls[n].bml_btl =
            mca_bml_base_btl_array_get_next(&bml_endpoint->btl_send);
        weight_total += sr->range_btls[n].bml_btl->btl_weight;
    }

    sr->range_btl_cnt = n;
    mca_pml_ob1_calc_weighted_length(sr->range_btls, n, send_length,
            weight_total);

    OPAL_THREAD_LOCK(&sendreq->req_send_range_lock);
    opal_list_append(&sendreq->req_send_ranges, (opal_list_item_t*)sr);
    OPAL_THREAD_UNLOCK(&sendreq->req_send_range_lock);
}

static inline mca_pml_ob1_send_range_t *
get_send_range_nolock(mca_pml_ob1_send_request_t* sendreq)
{
    opal_list_item_t *item;

    item = opal_list_get_first(&sendreq->req_send_ranges);

    if(opal_list_get_end(&sendreq->req_send_ranges) == item)
        return NULL;

    return (mca_pml_ob1_send_range_t*)item;
}

static inline mca_pml_ob1_send_range_t *
get_send_range(mca_pml_ob1_send_request_t* sendreq)
{
    mca_pml_ob1_send_range_t *range;

    OPAL_THREAD_LOCK(&sendreq->req_send_range_lock);
    range = get_send_range_nolock(sendreq);
    OPAL_THREAD_UNLOCK(&sendreq->req_send_range_lock);

    return range;
}

static inline mca_pml_ob1_send_range_t *
get_next_send_range(mca_pml_ob1_send_request_t* sendreq,
        mca_pml_ob1_send_range_t *range)
{
    OPAL_THREAD_LOCK(&sendreq->req_send_range_lock);
    opal_list_remove_item(&sendreq->req_send_ranges, (opal_list_item_t *)range);
    opal_free_list_return (&mca_pml_ob1.send_ranges, &range->base);
    range = get_send_range_nolock(sendreq);
    OPAL_THREAD_UNLOCK(&sendreq->req_send_range_lock);

    return range;
}

/**
 *  Schedule pipeline of send descriptors for the given request.
 *  Up to the rdma threshold. If this is a send based protocol,
 *  the rdma threshold is the end of the message. Otherwise, schedule
 *  fragments up to the threshold to overlap initial registration/setup
 *  costs of the rdma. Only one thread can be inside this function.
 */

int
mca_pml_ob1_send_request_schedule_once(mca_pml_ob1_send_request_t* sendreq)
{
    size_t prev_bytes_remaining = 0;
    mca_pml_ob1_send_range_t *range;
    int num_fail = 0;

    /* check pipeline_depth here before attempting to get any locks */
    if(true == sendreq->req_throttle_sends &&
       sendreq->req_pipeline_depth >= mca_pml_ob1.send_pipeline_depth)
        return OMPI_SUCCESS;

    range = get_send_range(sendreq);

    if (NULL != sendreq->rdma_frag) {
        /* this request was first attempted with RDMA but is now using send/recv */
        MCA_PML_OB1_RDMA_FRAG_RETURN(sendreq->rdma_frag);
        sendreq->rdma_frag = NULL;
    }

    while(range && (false == sendreq->req_throttle_sends ||
          sendreq->req_pipeline_depth < mca_pml_ob1.send_pipeline_depth)) {
        mca_pml_ob1_frag_hdr_t* hdr;
        mca_btl_base_descriptor_t* des;
        int rc, btl_idx;
        size_t size, offset, data_remaining = 0;
        mca_bml_base_btl_t* bml_btl;

        assert(range->range_send_length != 0);

        if(prev_bytes_remaining == range->range_send_length)
            num_fail++;
        else
            num_fail = 0;

        prev_bytes_remaining = range->range_send_length;

        if( OPAL_UNLIKELY(num_fail == range->range_btl_cnt) ) {
            /*TODO : assert(sendreq->req_pending == MCA_PML_OB1_SEND_PENDING_NONE); */
            add_request_to_send_pending(sendreq,
                    MCA_PML_OB1_SEND_PENDING_SCHEDULE, true);
            /* Note that request remains locked. send_request_process_pending()
             * function will call schedule_exclusive() directly without taking
             * the lock */
            return OMPI_ERR_OUT_OF_RESOURCE;
        }

cannot_pack:
        do {
            btl_idx = range->range_btl_idx;
            if(++range->range_btl_idx == range->range_btl_cnt)
                range->range_btl_idx = 0;
        } while(!range->range_btls[btl_idx].length);

        bml_btl = range->range_btls[btl_idx].bml_btl;
        /* If there is a remaining data from another BTL that was too small
         * for converter to pack then send it through another BTL */
        range->range_btls[btl_idx].length += data_remaining;
        size = range->range_btls[btl_idx].length;

        /* makes sure that we don't exceed BTL max send size */
        if(bml_btl->btl->btl_max_send_size != 0) {
            size_t max_send_size;
            if ((sendreq->req_send.req_base.req_convertor.flags & CONVERTOR_ACCELERATOR) && (bml_btl->btl->btl_accelerator_max_send_size != 0)) {
                max_send_size = bml_btl->btl->btl_accelerator_max_send_size - sizeof(mca_pml_ob1_frag_hdr_t);
            } else {
                max_send_size = bml_btl->btl->btl_max_send_size - sizeof(mca_pml_ob1_frag_hdr_t);
            }
            if (size > max_send_size) {
                size = max_send_size;
            }
        }

        /* pack into a descriptor */
        offset = (size_t)range->range_send_offset;
        opal_convertor_set_position(&sendreq->req_send.req_base.req_convertor,
                                    &offset);
        range->range_send_offset = (uint64_t)offset;

        data_remaining = size;
        MEMCHECKER(
            memchecker_call(&opal_memchecker_base_mem_defined,
                            sendreq->req_send.req_base.req_addr,
                            sendreq->req_send.req_base.req_count,
                            sendreq->req_send.req_base.req_datatype);
        );
        mca_bml_base_prepare_src(bml_btl, &sendreq->req_send.req_base.req_convertor,
                                 MCA_BTL_NO_ORDER, sizeof(mca_pml_ob1_frag_hdr_t),
                                 &size, MCA_BTL_DES_FLAGS_BTL_OWNERSHIP | MCA_BTL_DES_SEND_ALWAYS_CALLBACK |
                                 MCA_BTL_DES_FLAGS_SIGNAL, &des);
        MEMCHECKER(
            memchecker_call(&opal_memchecker_base_mem_noaccess,
                            sendreq->req_send.req_base.req_addr,
                            sendreq->req_send.req_base.req_count,
                            sendreq->req_send.req_base.req_datatype);
        );

        if( OPAL_UNLIKELY(des == NULL || size == 0) ) {
            if(des) {
                /* Converter can't pack this chunk. Append to another chunk
                 * from other BTL */
                mca_bml_base_free(bml_btl, des);
                range->range_btls[btl_idx].length -= data_remaining;
                goto cannot_pack;
            }
            continue;
        }

        des->des_cbfunc = mca_pml_ob1_frag_completion;
        des->des_cbdata = sendreq;

        /* setup header */
        hdr = (mca_pml_ob1_frag_hdr_t*)des->des_segments->seg_addr.pval;
        mca_pml_ob1_frag_hdr_prepare (hdr, 0, range->range_send_offset, sendreq,
                                      sendreq->req_recv.lval);

        ob1_hdr_hton(hdr, MCA_PML_OB1_HDR_TYPE_FRAG,
                sendreq->req_send.req_base.req_proc);

#if OMPI_WANT_PERUSE
         PERUSE_TRACE_COMM_OMPI_EVENT(PERUSE_COMM_REQ_XFER_CONTINUE,
                 &(sendreq->req_send.req_base), size, PERUSE_SEND);
#endif  /* OMPI_WANT_PERUSE */

         /* At this point, check to see if the BTL is doing an asynchronous
          * copy.  This would have been initiated in the mca_bml_base_prepare_src
          * called above.  The flag is checked here as we let the hdr be
          * set up prior to checking.
          */
        if (des->des_flags & MCA_BTL_DES_FLAGS_ACCELERATOR_COPY_ASYNC) {
            OPAL_OUTPUT((-1, "Initiating async copy on FRAG frag=%p", (void *)des));
            /* Need to make sure BTL does not free frag after completion
             * of asynchronous copy as we still need to send the fragment. */
            des->des_flags &= ~MCA_BTL_DES_FLAGS_BTL_OWNERSHIP;
            /* Unclear that this flag needs to be set but to be sure, set it */
            des->des_flags |= MCA_BTL_DES_SEND_ALWAYS_CALLBACK;
            des->des_cbfunc = mca_pml_ob1_copy_frag_completion;
            range->range_btls[btl_idx].length -= size;
            range->range_send_length -= size;
            range->range_send_offset += size;
            OPAL_THREAD_ADD_FETCH32(&sendreq->req_pipeline_depth, 1);
            if(range->range_send_length == 0) {
                range = get_next_send_range(sendreq, range);
                prev_bytes_remaining = 0;
            }
            continue;
        }

        /* initiate send - note that this may complete before the call returns */
        rc = mca_bml_base_send(bml_btl, des, MCA_PML_OB1_HDR_TYPE_FRAG);
        if( OPAL_LIKELY(rc >= 0) ) {
            /* update state */
            range->range_btls[btl_idx].length -= size;
            range->range_send_length -= size;
            range->range_send_offset += size;
            OPAL_THREAD_ADD_FETCH32(&sendreq->req_pipeline_depth, 1);
            if(range->range_send_length == 0) {
                range = get_next_send_range(sendreq, range);
                prev_bytes_remaining = 0;
            }
        } else {
            mca_bml_base_free(bml_btl,des);
        }
    }

    return OMPI_SUCCESS;
}


/**
 * A put fragment could not be started. Queue the fragment to be retried later or
 * fall back on send/recv.
 */
static void mca_pml_ob1_send_request_put_frag_failed (mca_pml_ob1_rdma_frag_t *frag, int rc)
{
    mca_pml_ob1_send_request_t* sendreq = (mca_pml_ob1_send_request_t *) frag->rdma_req;
    mca_bml_base_btl_t *bml_btl = frag->rdma_bml;

    if (frag->retries < mca_pml_ob1.rdma_retries_limit && OMPI_ERR_OUT_OF_RESOURCE == rc) {
        /* queue the frag for later if there was a resource error */
        OPAL_THREAD_LOCK(&mca_pml_ob1.lock);
        opal_list_append(&mca_pml_ob1.rdma_pending, (opal_list_item_t*)frag);
        OPAL_THREAD_UNLOCK(&mca_pml_ob1.lock);
        return;
    }

#if OPAL_ENABLE_FT
    if(!ompi_proc_is_active(sendreq->req_send.req_base.req_proc)) {
        return;
    }
#endif /* OPAL_ENABLE_FT */
    /* tell receiver to deregister memory */
    mca_pml_ob1_send_fin (sendreq->req_send.req_base.req_proc, bml_btl,
                          frag->rdma_hdr.hdr_rdma.hdr_frag, 0, MCA_BTL_NO_ORDER,
                          OPAL_ERR_TEMP_OUT_OF_RESOURCE);

    /* send fragment by copy in/out */
    mca_pml_ob1_send_request_copy_in_out(sendreq, frag->rdma_hdr.hdr_rdma.hdr_rdma_offset,
                                         frag->rdma_length);
    /* if a pointer to a receive request is not set it means that
     * ACK was not yet received. Don't schedule sends before ACK */
    if (NULL != sendreq->req_recv.pval)
        mca_pml_ob1_send_request_schedule (sendreq);
}

/**
 *  An RDMA put operation has completed:
 *  (1) Update request status and if required set completed
 *  (2) Send FIN control message to the destination
 */

static void mca_pml_ob1_put_completion (mca_btl_base_module_t* btl, struct mca_btl_base_endpoint_t* ep,
                                        void *local_address, mca_btl_base_registration_handle_t *local_handle,
                                        void *context, void *cbdata, int status)
{
    mca_pml_ob1_rdma_frag_t *frag = (mca_pml_ob1_rdma_frag_t *) cbdata;
    mca_pml_ob1_send_request_t *sendreq = (mca_pml_ob1_send_request_t *) frag->rdma_req;
    mca_bml_base_btl_t *bml_btl = (mca_bml_base_btl_t *) context;

    /* check completion status */
    if( OPAL_UNLIKELY(OMPI_SUCCESS == status) ) {
        /* TODO -- read ordering */
        mca_pml_ob1_send_fin (sendreq->req_send.req_base.req_proc, bml_btl,
                              frag->rdma_hdr.hdr_rdma.hdr_frag, frag->rdma_length,
                              0, 0);

        /* check for request completion */
        OPAL_THREAD_ADD_FETCH_SIZE_T(&sendreq->req_bytes_delivered, frag->rdma_length);
        SPC_USER_OR_MPI(sendreq->req_send.req_base.req_ompi.req_status.MPI_TAG, (ompi_spc_value_t)frag->rdma_length,
                        OMPI_SPC_BYTES_SENT_USER, OMPI_SPC_BYTES_SENT_MPI);

        send_request_pml_complete_check(sendreq);
    } else {
        /* try to fall back on send/recv */
        mca_pml_ob1_send_request_put_frag_failed (frag, status);
    }

    if( sendreq->rdma_frag == frag ) {
        sendreq->rdma_frag = NULL;
    }
    MCA_PML_OB1_RDMA_FRAG_RETURN(frag);

    if( OPAL_LIKELY( OMPI_SUCCESS == status ) ) {
        MCA_PML_OB1_PROGRESS_PENDING(bml_btl);
    }
}

int mca_pml_ob1_send_request_put_frag( mca_pml_ob1_rdma_frag_t *frag )
{
    mca_pml_ob1_send_request_t *sendreq = (mca_pml_ob1_send_request_t *) frag->rdma_req;
    mca_btl_base_registration_handle_t *local_handle = NULL;
    mca_bml_base_btl_t *bml_btl = frag->rdma_bml;
    int rc;

    if (bml_btl->btl->btl_register_mem && NULL == frag->local_handle) {
        /* Check if the segment is already registered */
        for (size_t i = 0 ; i < sendreq->req_rdma_cnt ; ++i) {
            if (sendreq->req_rdma[i].bml_btl == frag->rdma_bml) {
                /* do not copy the handle to the fragment to avoid deregistring it twice */
                local_handle = sendreq->req_rdma[i].btl_reg;
                break;
            }
        }

        if (NULL == frag->local_handle) {
            /* Not already registered. Register the region with the BTL. */
            mca_bml_base_register_mem (bml_btl, frag->local_address, frag->rdma_length, 0,
                                       &frag->local_handle);

            if (OPAL_UNLIKELY(NULL == frag->local_handle)) {
                mca_pml_ob1_send_request_put_frag_failed (frag, OMPI_ERR_OUT_OF_RESOURCE);

                return OMPI_ERR_OUT_OF_RESOURCE;
            }

            local_handle = frag->local_handle;
        }
    }

    PERUSE_TRACE_COMM_OMPI_EVENT( PERUSE_COMM_REQ_XFER_CONTINUE,
                                  &(((mca_pml_ob1_send_request_t*)frag->rdma_req)->req_send.req_base), frag->rdma_length, PERUSE_SEND );

    rc = mca_bml_base_put (bml_btl, frag->local_address, frag->remote_address, local_handle,
                           (mca_btl_base_registration_handle_t *) frag->remote_handle, frag->rdma_length,
                           0, MCA_BTL_NO_ORDER, mca_pml_ob1_put_completion, frag);
    /* Count the bytes put even though they probably haven't been sent yet */
    SPC_RECORD(OMPI_SPC_BYTES_PUT, (ompi_spc_value_t)frag->rdma_length);
    if (OPAL_UNLIKELY(OMPI_SUCCESS != rc)) {
        mca_pml_ob1_send_request_put_frag_failed (frag, rc);
        if( sendreq->rdma_frag == frag ) {
            sendreq->rdma_frag = NULL;
        }
        MCA_PML_OB1_RDMA_FRAG_RETURN(frag);
        return rc;
    }

    return OMPI_SUCCESS;
}

/**
 *  Receiver has scheduled an RDMA operation:
 *  (1) Allocate an RDMA fragment to maintain the state of the operation
 *  (2) Call BTL prepare_src to pin/prepare source buffers
 *  (3) Queue the RDMA put
 */

void mca_pml_ob1_send_request_put (mca_pml_ob1_send_request_t *sendreq,
                                   mca_btl_base_module_t *btl,
                                   const mca_pml_ob1_rdma_hdr_t *hdr)
{
    mca_bml_base_endpoint_t *bml_endpoint = sendreq->req_endpoint;
    mca_pml_ob1_rdma_frag_t* frag;

    if(hdr->hdr_common.hdr_flags & MCA_PML_OB1_HDR_TYPE_ACK) {
        OPAL_THREAD_ADD_FETCH32(&sendreq->req_state, -1);
    }

    sendreq->req_recv.pval = hdr->hdr_recv_req.pval;

    if (NULL == sendreq->rdma_frag) {
        MCA_PML_OB1_RDMA_FRAG_ALLOC(frag);

        if( OPAL_UNLIKELY(NULL == frag) ) {
            /* send fragment by copy in/out */
            mca_pml_ob1_send_request_copy_in_out(sendreq,
                                                 hdr->hdr_rdma_offset, hdr->hdr_dst_size);
            /* if a pointer to a receive request is not set it means that
             * ACK was not yet received. Don't schedule sends before ACK */
            if(NULL != sendreq->req_recv.pval) {
                mca_pml_ob1_send_request_schedule(sendreq);
            }
            return;
        }
    } else {
        /* rget fallback on put */
        frag = sendreq->rdma_frag;
        sendreq->rdma_frag = NULL;
        sendreq->req_state = 0;
    }

    /* copy registration data */
    memcpy (frag->remote_handle, hdr + 1, btl->btl_registration_handle_size);

    frag->rdma_bml = mca_bml_base_btl_array_find(&bml_endpoint->btl_rdma, btl);
    frag->rdma_hdr.hdr_rdma = *hdr;
    frag->rdma_req = sendreq;
    frag->rdma_length = hdr->hdr_dst_size;
    frag->rdma_state = MCA_PML_OB1_RDMA_PUT;
    frag->remote_address = hdr->hdr_dst_ptr;
    frag->retries = 0;

    /* Get the address of the current offset. Note: at this time ob1 CAN NOT handle
     * non-contiguous RDMA. If that changes this code will be wrong. */
    opal_convertor_get_offset_pointer (&sendreq->req_send.req_base.req_convertor,
                                       hdr->hdr_rdma_offset, &frag->local_address);

    mca_pml_ob1_send_request_put_frag(frag);
}